st=>start: 开始|past:>http://www.baidu.com
e=>end: 结束|future:>http://www.baidu.com
io11=>inputoutput: 输入用户名密码
sub11=>subroutine: 查询数据库子程序
cond11=>condition: db中是否有此用户密码
op11=>operation: 用户登录，进入业务逻辑
op1=>operation: My Operation|past
op2=>operation: Stuff|current
sub1=>subroutine: My Subroutine|invalid
cond=>condition: Yes
or No?|approved:>http://www.baidu.com
c2=>condition: Good idea|rejected
io=>inputoutput: catch something...|future

st->io11->sub11->cond11->
cond11(no, right)->io11
cond11(yes, left)->op11
op11->e

st=>start: Start
e=>end
io0=>inputoutput: 输入用户密码
op1=>operation: 查询db是否有此用户密码
sub1=>subroutine: 返回登录页面逻辑
cond=>condition: Yes or No?
io=>inputoutput: 输入你要购买的东西
    
st->io0->op1->cond
cond(yes)->io->e
cond(no)->sub1(right)->io0

st=>start: 开始|past
e=>end: 结束|future
io0=>inputoutput: 输入用户名密码
sub0=>subroutine: 查询db此用户名|past
op2=>operation: 结束之前|current
sub1=>subroutine: 返回登录页面逻辑|invalid
cond=>condition: 有无此用户?|approved
c2=>condition: 验证密码正误|rejected
io=>inputoutput: 输入想要购买的东西|future

st->io0->sub0(right)->cond
cond(yes, right)->c2
cond(no)->sub1(right)->io0
c2(yes)->io->e
c2(no)->op2->e